Centrifuges are used in numerous fields, and in particular as geotechnical centrifuges for research or industrial work. In such cases, a centrifuge is used to simulate stresses to which structures may be subjected, e.g. under the effect of earthquakes, and various amounts of data are taken from tests performed on a model or prototype at reduced scale which is placed in a swinging basket suspended at the end of the rotary arm of the centrifuge. During testing in which model structures are subjected to forces which increase or alternate by virtue of the rotary arm of the centrifuge being rotated at different speeds of rotation or in alternating cycles, various measurements are performed on the scale model structures in order to design mathematical models representative of the behavior of the structures.
Testing often continues until the structure placed in the basket of the centrifuge collapses. This gives rise suddenly to a major unbalance in the centrifuge. In order to rebalance the centrifuge after the model has collapsed, it is necessary to stop the centrifuge in order to act on the mass or the location of the counterweights which are generally place on the oppostie end of the rotary arm to the basket containing the model being subjected to mechanical strength testing. Such rebalancing operations take a long time. Sometimes, the sudden unbalance generated by a model collapsing can even damage the centrifuge, thereby delaying further testing. It may also be observed that major unbalance can occur during testing even though a model under test has not collapsed. This happens, for example, when testing structures that co-operate with fluctuating masses of liquid, e.g. when testing dam or dyke structures.
The present invention seeks to remedy the above-mentioned drawbacks and to make it possible to detect and automatically compensate an unbalance that may appear in a centrifuge in operation in a manner which is simple and effective and which does not require the centrifuge to be stopped.